Therapeutic potential of mipomersen in the management of familial hypercholesterolaemia

Lipoprotein(a) in patients with breast cancer after chemotherapy: exploring potential strategies for cardioprotection

Developments in neoadjuvant and adjuvant chemotherapy (CHT) have led to an increase in the number of breast cancer survivors. The determination of an appropriate follow-up for these patients is of increasing importance. Deaths due to cardiovascular disease (CVD) are an important part of mortality in patients with breast cancer.This review suggests that chemotherapeutic agents may influence lipoprotein(a) (Lp(a)) concentrations in breast cancer survivors after CHT based on many convincing evidence from epidemiologic and observational researches. Usually, the higher the Lp(a) concentration, the higher the median risk of developing CVD. However, more clinical trial results are needed in the future to provide clear evidence of a possible causal relationship. This review also discuss the existing and emerging therapies for lowering Lp(a) concentrations in the clinical setting. Hormone replacement therapy, statins, proprotein convertase subtilisin/kexin-type 9 (PCSK9) inhibitors, Antisense oligonucleotides, small interfering RNA, etc. may reduce circulating Lp(a) or decrease the incidence of CVD.

Modification of Lipid-Based Nanoparticles: An Efficient Delivery System for Nucleic Acid-Based Immunotherapy

Lipid-based nanoparticles (LBNPs) are biocompatible and biodegradable vesicles that are considered to be one of the most efficient drug delivery platforms. Due to the prominent advantages, such as long circulation time, slow drug release, reduced toxicity, high transfection efficiency, and endosomal escape capacity, such synthetic nanoparticles have been widely used for carrying genetic therapeutics, particularly nucleic acids that can be applied in the treatment for various diseases, including congenital diseases, cancers, virus infections, and chronic inflammations. Despite great merits and multiple successful applications, many extracellular and intracellular barriers remain and greatly impair delivery efficacy and therapeutic outcomes. As such, the current state of knowledge and pitfalls regarding the gene delivery and construction of LBNPs will be initially summarized. In order to develop a new generation of LBNPs for improved delivery profiles and therapeutic effects, the modification strategies of LBNPs will be reviewed. On the basis of these developed modifications, the performance of LBNPs as therapeutic nanoplatforms have been greatly improved and extensively applied in immunotherapies, including infectious diseases and cancers. However, the therapeutic applications of LBNPs systems are still limited due to the undesirable endosomal escape, potential aggregation, and the inefficient encapsulation of therapeutics. Herein, we will review and discuss recent advances and remaining challenges in the development of LBNPs for nucleic acid-based immunotherapy.

BIOANALYSIS AND BIOTRANSFORMATION OF OLIGONUCLEOTIDE THERAPEUTICS BY LIQUID CHROMATOGRAPHY-MASS SPECTROMETRY

Since 2016, eight new oligonucleotide therapies have been approved which has led to increased interest in oligonucleotide analysis. There is a particular need for powerful bioanalytical tools to study the metabolism and biotransformation of these molecules. This review provides the background on the biological basis of these molecules as currently used in therapies. The article also reviews the current state of analytical methodology including state of the art sample preparation techniques, liquid chromatography-mass spectrometry methods, and the current limits of detection/quantitation. Finally, the article summarizes the challenges in oligonucleotide bioanalysis and provides future perspectives for this emerging field. © 2020 John Wiley & Sons Ltd.

Development of Antisense Oligonucleotide Gapmers for the Treatment of Dyslipidemia and Lipodystrophy

Although technological advances in molecular genetics over the last few decades have greatly expedited the identification of mutations in many genetic diseases, the translation of the genetic mechanisms into a clinical setting has been quite challenging, with a minimum number of effective treatments available. The advancements in antisense therapy have revolutionized the field of neuromuscular disorders as well as lipid-mediated diseases. With the approval of splice-switching antisense oligonucleotide (AO) therapy for nusinersen and eteplirsen for the treatment of spinal muscular atrophy (SMA) and Duchenne muscular dystrophy (DMD), several modified AOs are now being evaluated in clinical trials for the treatment of a number of disorders. In order to activate RNase H-mediated cleavage of the target mRNA, as well as to increase the binding affinity and specificity, gapmer AOs are designed that have a PS backbone flanked with the modified AOs on both sides. Mipomersen (trade name Kynamro), a 2'-O-methoxyethyl (MOE) gapmer, was approved by the Food and Drug Administration (FDA) for the treatment of homozygous familial hypercholesterolemia (HoFH) in 2013. Volanesorsen, another 20-mer MOE gapmer has shown to be successful in lowering the levels of triglycerides (TGs) in several lipid disorders and has received conditional approval in the European Union for the treatment of Familial chylomicronemia syndrome (FCS) in May 2019 following successful results from phase II/III clinical trials. This chapter focuses on the clinical applications of gapmer AOs for genetic dyslipidemia and lipodystrophy.

Smart Nanocarriers for the Delivery of Nucleic Acid-Based Therapeutics: A Comprehensive Review

Nucleic acid-based therapies are promising therapeutics for the treatment of several systemic disorders, and they offer an exciting opportunity to address emerging biological challenges. The scope of nucleic acid-based therapeutics in the treatment of multiple disease states including cancers has been widened by recent progress in Ribonucleic acids (RNA) biology. However, cascades of systemic and intracellular barriers, including rapid degradation, renal clearance, and poor cellular uptake, hinder the clinical effectiveness of nucleic acid-based therapies. These barriers can be circumvented by utilizing advanced smart nanocarriers that efficiently deliver and release the encapsulated nucleic acids into the target tissues. This review describes the current status of clinical trials on nucleic acid-based therapeutics and highlights representative examples that provide an overview on the current and emerging trends in nucleic acid-based therapies. A better understanding of the design of advanced nanocarriers is essential to promote the translation of therapeutic nucleic acids into a clinical reality.

Therapeutic Oligonucleotides Targeting Liver Disease: TTR Amyloidosis

The liver has become an increasingly interesting target for oligonucleotide therapy. Mutations of the gene encoding transthyretin (TTR), expressed in vast amounts by the liver, result in a complex degenerative disease, termed familial amyloid polyneuropathy (FAP). Misfolded variants of TTR are linked to the establishment of extracellular protein deposition in various tissues, including the heart and the peripheral nervous system. Recent progress in the chemistry and formulation of antisense (ASO) and small interfering RNA (siRNA) designed for a knockdown of TTR mRNA in the liver has allowed to address the issue of gene-specific molecular therapy in a clinical setting of FAP. The two therapeutic oligonucleotides bind to RNA in a sequence specific manner but exploit different mechanisms. Here we describe major developments that have led to the advent of therapeutic oligonucleotides for treatment of TTR-related disease.

Delivery of therapeutic oligonucleotides with cell penetrating peptides

Oligonucleotide-based drugs have received considerable attention for their capacity to modulate gene expression very specifically and as a consequence they have found applications in the treatment of many human acquired or genetic diseases. Clinical translation has been often hampered by poor biodistribution, however. Cell-penetrating peptides (CPPs) appear as a possibility to increase the cellular delivery of non-permeant biomolecules such as nucleic acids. This review focuses on CPP-delivery of several classes of oligonucleotides (ONs), namely antisense oligonucleotides, splice switching oligonucleotides (SSOs) and siRNAs. Two main strategies have been used to transport ONs with CPPs: covalent conjugation (which is more appropriate for charge-neutral ON analogues) and non-covalent complexation (which has been used for siRNA delivery essentially). Chemical synthesis, mechanisms of cellular internalization and various applications will be reviewed. A comprehensive coverage of the enormous amount of published data was not possible. Instead, emphasis has been put on strategies that have proven to be effective in animal models of important human diseases and on examples taken from the authors' own expertise.

LC-MS of oligonucleotides: applications in biomedical research

Recent findings have elucidated numerous novel biological functions for oligonucleotides. Current standard methods for the study of oligonucleotides (i.e., hybridization and PCR) are not fully equipped to deal with the experimental needs arising from these new discoveries. More importantly, as the intracellular capacity of oligonucleotides is being harnessed for biomedical applications, alternative bioanalytical techniques become indispensable in order to comply with ever-increasing regulatory requirements. Owing to its ability to detect oligonucleotides independent of their sequence, LC-MS is emerging as the analytical method of choice for oligonucleotides. In this article, the current applications of LC-MS in the analysis of oligonucleotides, with an emphasis on RNA therapeutics and biomarkers, will be examined. In addition, the theoretical framework of oligonucleotide ESI is carefully inspected with the purpose of identifying the contributing factors to MS signal intensity.

Going beyond the liver: progress and challenges of targeted delivery of siRNA therapeutics

Therapeutic gene silencing promises significant progress in pharmacotherapy, including considerable expansion of the druggable target space and the possibility for treating orphan diseases. Technological hurdles have complicated the efficient use of therapeutic oligonucleotides, and siRNA agents suffer particularly from insufficient pharmacokinetic properties and poor cellular uptake. Intense development and evolution of delivery systems have resulted in efficient uptake predominantly in liver tissue, in which practically all nanoparticulate and liposomal delivery systems show the highest accumulation. The most efficacious strategies include liposomes and bioconjugations with N-acetylgalactosamine. Both are in early clinical evaluation stages for treatment of liver-associated diseases. Approaches for achieving knockdown in other tissues and tumors have been proven to be more complicated. Selective targeting to tumors may be enabled through careful modulation of physical properties, such as particle size, or by taking advantage of specific targeting ligands. Significant barriers stand between sufficient accumulation in other organs, including endothelial barriers, cellular membranes, and the endosome. The brain, which is shielded by the blood-brain barrier, is of particular interest to facilitate efficient oligonucleotide therapy of neurological diseases. Transcytosis of the blood-brain barrier through receptor-specific docking is investigated to increase accumulation in the central nervous system. In this review, the current clinical status of siRNA therapeutics is summarized, as well as innovative and promising preclinical concepts employing tissue- and tumor-targeted ligands. The requirements and the respective advantages and drawbacks of bioconjugates and ligand-decorated lipid or polymeric particles are discussed.

Familial hypercholesterolemia: developments in diagnosis and treatment

BACKGROUND

Familial hypercholesterolemia (FH) is a congenital disorder of lipid metabolism characterized by a marked elevation of the plasma concentration of LDL (low-density lipoprotein) cholesterol beginning in childhood and by the early onset of coronary heart disease. It is among the commonest genetic disorders, with an estimated prevalence in Germany of at least 1 per 500 persons.

METHOD

Review of pertinent literature retrieved by a selective search.

RESULTS

FH is underdiagnosed and undertreated in Germany. It is clinically diagnosed on the basis of an elevated LDL cholesterol concentration (>190 mg/dL [4.9 mmol/L]), a family history of hypercholesterolemia, and early coronary heart disease, or the demonstration of xanthomas. The gold standard of diagnosis is the identification of the underlying genetic defect, which is possible in 80% of cases and enables the identification of affected relatives of the index patient. The recommended goals of treatment, based on the results of observational studies, are to lower the LDL cholesterol concentration by at least 50% or to less than 100 mg/dL (2.6 mmol/L) (for children: <135 mg/dL [3.5 mmol/L]). The target value is lower for patients with clinically overt atherosclerosis (<70 mg/dL [1.8 mmol/L]). Statins, combined with a health-promoting lifestyle, are the treatment of choice. Lipoprotein apheresis is used in very severe cases; its therapeutic effects on clinical endpoints and its side effect profile have not yet been documented in randomized controlled trials.

CONCLUSION

Familial hypercholesterolemia is a common disease that can be diagnosed simply and reliably on clinical grounds and by molecular genetic testing. Timely diagnosis and appropriate treatment can lower the risk of atherosclerosis in heterozygous patients to that of the general population.

Looking into the Crystal Ball—Upcoming Drugs for Dyslipidemia

Dyslipidaemia is a critical risk factor for the development of cardiovascular complications such as ischemic heart disease and stroke. Although statins are effective anti-dyslipidemic drugs, their usage is fraught with issues such as failure of adequate lipid control in 30% of cases and intolerance in select patients. The limited potential of other alternatives such as fibrates, bile acid sequestrants and niacin has spurred the search for novel drug molecules with better efficacy and safety. CETP inhibitors such as evacetrapib and anacetrapib have shown promise in raising HDL besides LDL lowering property. Microsomal triglyceride transfer protein (MTP) inhibitors such as lomitapide and Apo CIII inhibitors such as mipomersen have recently been approved in Familial Hypercholesterolemia but experience in the non-familial setting is pretty much limited. One of the novel anti-dyslipidemic drugs which is greatly anticipated to make a mark in LDL-C control is the PCSK9 inhibitors. Some of the anti-dyslipidemic drugs which work by PCSK9 inhibition include evolocumab, alirocumab and ALN-PCS. Other approaches that are being given due consideration include farnesoid X receptor modulation and Lp-PLA2 inhibition. While it may not be an easy proposition to dismantle statins from their current position as a cholesterol reducing agent and as a drug to reduce coronary and cerebro-vascular atherosclerosis, our improved understanding of the disease and appropriate harnessing of resources using sound and robust technology could make rapid in-roads in our pursuit of the ideal anti-dyslipidemic drug.

Mipomersen sodium: first global approval

Mipomersen sodium (Kynamro™) (henceforth mipomersen) is a second-generation antisense oligonucleotide inhibitor of apolipoprotein B-100, which is the main structural component of atherogenic lipid particles. Mipomersen is administered via subcutaneous injection and is indicated as adjunctive treatment for homozygous familial hypercholesterolaemia (HoFH). The drug was developed by Isis Pharmaceuticals, which now collaborates with Genzyme Corporation for on-going development and product marketing. Multinational phase III trials of mipomersen as adjunctive therapy were completed in patients with HoFH, severe FH, heterozygous FH (HeFH) with coronary artery disease (CAD), and in those with hypercholesterolaemia at high risk of CAD. Mipomersen 200 mg once weekly has been approved in the USA as an adjunct to lipid-lowering medications and diet in HoFH patients and is undergoing regulatory review in the EU for the same indication. Genzyme is also conducting a multinational phase III, open-label extension study to evaluate long-term treatment in HoFH and HeFH patients, as well as a multinational trial to evaluate a three-times-per-week mipomersen regimen in patients with severe FH. This article summarises the milestones in the development of once-weekly, subcutaneous mipomersen leading to this first approval.

Antisense oligonucleotides on neurobehavior, respiratory, and cardiovascular function, and hERG channel current studies

INTRODUCTION

Safety Pharmacology studies were conducted in mouse, rat, and non-human primate to determine in vivo effects of antisense oligonucleotides (ASOs) on the central nervous system, respiratory system, and cardiovascular system. Effects on the hERG potassium channel current was evaluated in vitro.

METHODS

ASOs contained terminal 2'-O-methoxyethyl nucleotides, central deoxy nucleotides, and a phosphorothioate backbone. Neurobehavior was evaluated by Functional Observatory Battery in rodents. Respiratory function was directly measured in rodents by plethysmograph; respiratory rate and blood gases were measured in monkey. Basic cardiovascular endpoints were measured in rat; cardiovascular evaluation in monkey involved implanted telemetry units. In single and repeat dose studies ASOs were administered by subcutaneous injection at up to 300 mg/kg, 250 mg/kg, and 40 mg/kg in mouse, rat, or monkey, respectively. Assays were performed in HEK293 or CHO-K1 cells, stably transfected with hERG cDNA, at ASO concentrations of up to 300 μM.

RESULTS

No apparent effects were noted for respiratory or CNS function. Continuous monitoring of the cardiovascular system in monkey demonstrated no ASO-related changes in blood pressures, heart rate, or ECG and associated parameters (i.e., QRS duration). Specific assessment of the hERG potassium channel indicated no potential for actions on ventricular repolarization or modest effects only at excessive concentrations.

DISCUSSION

The absence of direct actions on neurobehavior and respiratory function associated with the administration of ASOs in safety pharmacology core battery studies is consistent with published toxicology studies. The combination of in vitro hERG studies and in vivo studies in rat and monkey are consistent with no direct actions by ASOs on cardiac cell function or electrical conduction at relevant concentrations and dose levels. Taken as a whole, dedicated studies focused on the safety pharmacology of specific organ systems do not appear to add significant data for interpretation of potential adverse effects. The need for dedicated studies for future ASOs in the same class is questionable, as a more encompassing data set can be collected in repeat dose and longer-term toxicology studies.

Oligonucleotide conjugates for therapeutic applications

Insufficient pharmacokinetic properties and poor cellular uptake are the main hurdles for successful therapeutic development of oligonucleotide agents. The covalent attachment of various ligands designed to influence the biodistribution and cellular uptake or for targeting specific tissues is an attractive possibility to advance therapeutic applications and to expand development options. In contrast to advanced formulations, which often consist of multiple reagents and are sensitive to a variety of preparation conditions, oligonucleotide conjugates are defined molecules, enabling structure-based analytics and quality control techniques. This review gives an overview of current developments of oligonucleotide conjugates for therapeutic applications. Attached ligands comprise peptides, proteins, carbohydrates, aptamers and small molecules, including cholesterol, tocopherol and folic acid. Important linkage types and conjugation methods are summarized. The distinct ligands directly influence biochemical parameters, uptake mechanisms and pharmacokinetic properties.

Novel pharmacotherapies of familial hyperlipidemia

Familial hyperlipidemia is an inherited metabolic disorder characterized by elevated lipid and/or lipoprotein levels in the blood. Despite improvements in lipid-lowering therapy during the last decades, it still remains a substantial contributor to the incidence of cardiovascular disease since patients on current conventional therapies do not achieve their target LDL-cholesterol levels. With a view to lower LDL-cholesterol levels, a number of new therapeutic strategies have been developed over recent years. In this review, we provide an overview of these treatment options that are currently in clinical development and may offer alternative or adjunctive therapies for this high-risk population.

Familial hypercholesterolemia in children and adolescents

PURPOSE OF REVIEW

This review provides an update and highlights the controversies regarding recent advances and recommendations regarding screening, diagnosis and treatment of children and adolescents with familial hypercholesterolemia.

RECENT FINDINGS

Both general cardiovascular risk and specific familial hypercholesterolemia guidelines for children and adolescents have recently been released. Universal lipid screening of children has been recommended, in addition to targeted screening. The role of genetic testing for targeted screening and diagnostic confirmation is less clear. Although lifestyle therapy remains of key importance, increasing evidence of safety and efficacy support the use of statin therapy. Early therapy has been associated with improvements in noninvasive measures of early atherosclerosis in children, which likely can be extrapolated to improved freedom from cardiovascular disease events over the lifespan, as has been observed in adults. The new guidelines provide general and specific recommendations as to how family history and additional risk factors and risk conditions should be incorporated in decisions regarding initiation of statin therapy at LDL-cholesterol cutpoints. Emerging evidence from observational studies are beginning to address concerns regarding the initiation at young ages and longer-term efficacy and safety.

SUMMARY

Children and adolescents with familial hypercholesterolemia can be identified and effective therapy with a statin initiated with consideration of the patients' overall cardiovascular risk profile, remaining mindful of the uncertainties regarding long-term safety.